How to get Real IP from Visitor? [duplicate]

Question

Try this php code.

<?PHP

function getUserIP()
{
    // Get real visitor IP behind CloudFlare network
    if (isset($_SERVER["HTTP_CF_CONNECTING_IP"])) {
              $_SERVER['REMOTE_ADDR'] = $_SERVER["HTTP_CF_CONNECTING_IP"];
              $_SERVER['HTTP_CLIENT_IP'] = $_SERVER["HTTP_CF_CONNECTING_IP"];
    }
    $client  = @$_SERVER['HTTP_CLIENT_IP'];
    $forward = @$_SERVER['HTTP_X_FORWARDED_FOR'];
    $remote  = $_SERVER['REMOTE_ADDR'];

    if(filter_var($client, FILTER_VALIDATE_IP))
    {
        $ip = $client;
    }
    elseif(filter_var($forward, FILTER_VALIDATE_IP))
    {
        $ip = $forward;
    }
    else
    {
        $ip = $remote;
    }

    return $ip;
}


$user_ip = getUserIP();

echo $user_ip; // Output IP address [Ex: 177.87.193.134]


?>

This is the most common technique I've seen:

function getUserIP() {
    if( array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER) && !empty($_SERVER['HTTP_X_FORWARDED_FOR']) ) {
        if (strpos($_SERVER['HTTP_X_FORWARDED_FOR'], ',')>0) {
            $addr = explode(",",$_SERVER['HTTP_X_FORWARDED_FOR']);
            return trim($addr[0]);
        } else {
            return $_SERVER['HTTP_X_FORWARDED_FOR'];
        }
    }
    else {
        return $_SERVER['REMOTE_ADDR'];
    }
}

Note that it does not guarantee it you will get always the correct user IP because there are many ways to hide it.

This is my approach:

 function getRealUserIp(){
    switch(true){
      case (!empty($_SERVER['HTTP_X_REAL_IP'])) : return $_SERVER['HTTP_X_REAL_IP'];
      case (!empty($_SERVER['HTTP_CLIENT_IP'])) : return $_SERVER['HTTP_CLIENT_IP'];
      case (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) : return $_SERVER['HTTP_X_FORWARDED_FOR'];
      default : return $_SERVER['REMOTE_ADDR'];
    }
 }

How to use:

$ip = getRealUserIp();

Proxies may send a HTTP_X_FORWARDED_FOR header but even that is optional.

Also keep in mind that visitors may share IP addresses; University networks, large companies and third-world/low-budget ISPs tend to share IPs over many users.